Which phenomenon explains why a sound wave can be heard around a corner even if the direct path is blocked?

• A. Diffraction
• B. Reflection
• C. Refraction
• D. Dispersion

Answer: (A)

When a wave meets an obstacle, it doesn’t just stop at the edge. It spreads or bends around the obstacle, a behavior called diffraction. For sound, the wavelengths are long enough that the waves can bend around corners and small openings, allowing energy to reach the other side even when the direct path is blocked. This is why you can hear a voice or music coming from around a corner. The amount of bending is greater for longer wavelengths, so everyday sounds easily diffract around objects like walls and doorways. Other phenomena—reflection (bouncing off surfaces), refraction (bending when moving between media), and dispersion (separation of colors by wavelength)—don’t explain hearing around corners in the same way.